Never used 'em, or water treatment chemicals, or wasted time(in my opinion) boiling water for drinking. Result: Never been sick in BWCAW/Quetico in over 30 years. Know a lot of guides and outfitters, never talked to one who actually uses them himself, even though some provide them to customers. Some think they also strain beneficial nutrients out of the water (slightly tongue-in-cheek). But, if it makes you feel more comfortable, have at it. I certainly do purify my drinking water when I'm camping in the Rockies, Tetons, and Wind River Range. I've only read/heard of one confirmed case of Giardisis in the BWCAW ever, and none in Quetico. Considering the numbers of people who drink water from those parks every year, that strikes me as remarkable and as a pretty good indicator of the real threat. Although there are plenty of beaver and other potential vectors present, simply use common sense in choosing whence you draw your drinking water, eh? Happy Paddling! Jeff

I totally agree with Jeff, though I only have twenty years experience myself.

Agree with Jeff -- After 35 years of trips to the Quetico, have never used a filter.

Now, I always bring one and usually use it. About 8 years ago I experienced a mild case of giardia or some other type of organism after a late summer Quetico trip. Up to that point, I had never boiled or used a filter and instead relied on the common sense method of choosing water sources carefully. My case really wasn't very intense, but my stomach felt gurgly and bloated for about 3 weeks following that trip. I still generally agree with Jeff and if I forgot my filter or it broke, I really wouldn't worry about it too much.

I use a filter...It would ruin the trip if you became sick and it beats tablets. also, if you do forget it, i don't think it's a big problem

If you ever get giardia after a trip you will not forget to bring it. Peace of mind is also a plus... I put mine in my pack and leave it there so I will not forget it and check it before I go.